WinNonlin for Win95/WinNT (32-bit)
(Nonlinear Least Squares Analysis of Sedimentation Equilibrium Data)

Sedimentation Equilibrium Equation:
Data is fitted by the WinNonlin program to the following equation,
,
where dc is the concentration offset of the first data point (this is generally 0 for absorption data and some arbitrary value for interference data), q(i) is the degree of association for the ith associated species, Ci(r) is the concentration of the ith species at radius r, K1,i is the equilibrium constant for the association of monomer to the q(i)-mer, C1(r) is the concentration of the monomer at radius r, n is the total number of species present in the model being used for fitting the data, and can be between 1 (no association) and 5 for the current version of WinNonlin.
The variable C1(r) may be expanded to
,
where C1,0 is the monomer concentration at the first point of the data set (the natural logarithm of this is used by the program as LnA), x, x0 are the value of r2/2 and r2/2 at the first point of the data set (used as a reference position), B is the colligative second virial coefficient with the assumption of  gi = (g1)q(i), and s is the reduced molecular weight as defined by
,
where M1 is the monomer molecular weight,  is the partial specific volume, r is the solvent density and w is the rotor speed in radians per sec.  The variables that can be fitted by WinNonlin are dc (as deltaY), C1,0 (as LnA), q(i) (as Ni ), K1,i (as LnKi), s and B.

This version of Nonlin has been adapted for PCs running Win95 or WinNT (Workstation) from the OpenVMS version.  There is a maximum of 15 data sets and/or a total of 8000 data points.


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